1. Scope of Invention
This invention relates generally to devices for sanding and finishing drywall installations, and more particularly to a device for cleaning and finishing outside bullnose joints between adjacent sheets of drywall.
2. Prior Art
There are a number of prior art devices used for finishing drywall installation corners and surfaces. Some of these devices known to applicants are directed to the application of cementious drywall filler compound; the majority of these devices, however, are directed to the sanding, scraping or finishing of the cured drywall compound prior to painting or wallpapering the finished drywall surfaces.
The following U.S. patents are known to applicant which generally fit into this category of prior art devices:
U.S. Pat. No. 5,368,461 Murphy
All of these above prior art devices are either adapted to fill or finish flat drywall surfaces or inside or outside drywall joint areas which have sharp or crisp inside or outside corners, respectively.
A recently introduced feature for drywall outside corner joints is typically referred to as a xe2x80x9cbullnosexe2x80x9d cornerbead or joint. These outside radiused cornerbeads are formed of elongated metal strips which define an arcuate or radiused quarter circle sector or other similar sector cylindrical surface and are attached to the adjacent aligned edges of drywall panels.
The invention disclosed in U.S. Pat. No. 5,638,570 invented by Gruner teaches a drywall bullnose cleaner tool which scrapes excess filler compound from the radiused surfaces of an outside bullnose cornerbead of such a drywall installation. However, scraping action may not be rest suited for optimal smooth finishing of the bullnose cornerbead. Another device for the scraping, cleaning and finishing of bullnose cornerbeads is disclosed by Stolzfus in U.S. Pat. No. 392,484. Again, the scraping of the cylindrical bullnose surface is not fully effective in producing ha smooth, high quality finished surface ready for painting.
I was recently co-inventor of two U.S. patent, U.S. 5,993,306 and U.S. Des. 411,672. These devices generally teach a cleaning and finishing device for bullnose cornerbeads or joints which more gently and uniformly abrades away excess cured or hardened drywall filler compound without concern for overly abrading or grooving the drywall filler compound immediately adjacent the side margins of the metal bullnose cornerbead. Further, by including a somewhat resilient or compliant abrasive fibrous pad which accomplishes the cleaning and finishing action, any non-uniformity of the bullnose joint is easily accommodated.
The following additional prior art references are known to applicant as follows:
The later three of these references are also directed to the sanding of rounded bullnose cornerbeads as is intended for the present invention. However, all have structural features and limitations which render them generally ineffective and even damaging to the filler plaster immediately adjacent to the hard typically metallic surface of the bullnose cornerbead.
Additionally, as disclosed in my prior ""306 patent, the preferred abrasive medium was in the form of an open non-woven fibrous abrasive material such as that known as SCOTCH-BRITE by the 3M Company. Although this abrasive medium has offered a substantial improvement over conventional sanding paper against a hard radius or arcuate support surface, nonetheless the compressibility of the SCOTCH-BRITE material has not been ideal for the intended objective of removing all excess filler material from the bullnose corner without abrading the adjacent filler material.
The present invention provides still further improvement and sanding accuracy in cleaning excess material from bullnose cornerbeads while avoiding the excess abrasion and grooving of the drywall filler compound immediately adjacent the margins of the bullnose cornerbead.
This invention is directed to a device for abrading and finishing excess cured filler material from a bullnose cornerbead which forms an outside corner joint between immediately adjacent sheets of drywall. The device includes an elongated rigid body having a generally concave-shaped central longitudinal portion which receives a highly compressible thick foam-backed adhesive member which is preferably substantially coextensive with, and arcuately compressibly formable to match the radiused bullnose joint contour. Two spaced parallel guide rails extend longitudinally of the device adjacent each side margin of the central longitudinal portion which, in cooperation with the compressible abrasive member is mateingly engageable against the bullnose corner to substantially match the outside corner angle between the adjacent drywall sheets when the device is pressed firmly against the bullnose corner.
It is therefore an object of this invention to provide an improved sanding and cleaning device for removing and finishing bullnose cornerbead joints of drywall installations.
It is another object of this invention to provide a device for sanding and cleaning excess drywall filler or fairing compound from metal strips which form radiused bullnose joints between adjacent drywall panels.
It is still another object of this invention to provide a device for sanding and cleaning bullnose joints of drywall installations which readily accommodate any irregularity in the metallic strip forming these bullnose joints.
It is a further object of this invention to provide a device for sanding and cleaning excess drywall filler compounds from bullnose corner joints which include a replaceable elongated highly compressible abrasive pad or member.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with reference to the accompanying drawings.